M.N.
I exclusively breast fed my son for what seemed like forever (especially after having my first who weaned herself at 9 months). I had no intentions of nursing him past 15 months but it went on, and on, until he was about 2, when we were finally able to stop. He still, at age 5, has an attachment to my breasts and if he is really tired, scared or hurt - goes right for them. It used to drive me completely insane because it was all the time. We stopped nursing but he replaced that time with touching and snuggling with my breasts. Gradually, he stopped except for in extreme situations. One thing that helped was gently but constantly removing his hands from going down or up my shirt and holding his hands, lovingly but tightly.
Take care and good luck!